Circuit breaker having switch arm mounted on fluid conducting bearing



Dec. 17, 1957 L. J. LINDE CIRCUIT BREAKER HAVING SWITCH ARM.MOUNTED ON Filed 001;. 6, 1953 FLUID CONDUCTING BEARING 4 2 F j 0 2 i Y a o o z 9 i ZS I 5 O F I I 2 7A 5 2 Sheets-Sheet l 0 E 'fi 59 O a 5/- 52 9" I :IliIliQIILL Dec. 17, 1957 L. J. LINDE 2,816,993

. CIRCUIT BREAKER HAVING SWITCH ARM MOUNTED ON FLUID counucwmc BEARING Filed 001:. 6, 1953 2 Sheets-Sheet 2 United States Patent CIRCUIT BREAKER HAVING SWITCH ARM MOUNTED N FLUID CONDUCTING BEARING Leonard J. Linde, Needham, Mass, assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

Application October 6, 1953, Serial No. 384,489

8 Claims. (Cl. 200-148) This invention relates to electric circuit interrupting devices, and more particularly to air circuit breakers of the magnetic blowout type.

Heretofore, low current arcs in circuit breakers of the magnetic blowout type have been extinguished by pneumatic devices operatively connected to the movable contact structure. These pneumatic devices have been arranged so that a jet of air is directed across the arc in accordance with separation of the contacts. This air jet is intended to interrupt low current arcs which ordinarily tend to hang on due to the comparatively weak blowout field and to drive the are into the arc chute proper where it is more effectively cooled and extinguished.

In the practical application of this type of air jet action difficulties have been encountered. The pneumatic device, usually a cylinder and piston, is at ground potential whereas the means for transferring the blast of fluid under pressure from the pneumatic device to the arcing zone is exposed to the are at system potential. Therefore, at least a part of the fluid transfer means or the pneumatic means must be of insulating material. Insulating material is usually weak structurally and the problem associated with this type of circuit breaker structure is to provide a circuit breaker pneumatic means for extinguishing the are which will absorb the shock of numerous arc interrupting actions without rapid depreciation and frequent maintenance. Further, the circuit breaker structure must be protected from damage by flashover in the event that the fluid conducting means should break.

In accordance with this invention, a new and improved compact circuit breaker structure is provided comprising a stationary arcing contact and a. pivoted switch arm having a movable arcing contact mounted at one end thereof. A hollow fluid conducting stationary trunnion member or any other suitable form of bearing is provided for the switch arm. Pneumatic means for extinguishing an are drawn between the arcing contacts are connected through a tubular member of insulating material to the hearing. A second tubular member connected at one end to the bearing and terminating at its other end in a nozzle in the zone of arc initiation is used to direct the jet of fluid under pressure from the bearing to the desired location in the arcing zone of the circuit breaker structure.

It is, therefore, one object of the present invention to provide a new and improved arc interrupting device which is efficient in operation throughout the entire rated current range of the breaker.

Another object of the present invention is to provide a new and improved circuit breaker structure which is compact and rugged in design, economical to manufacture and which is particularly adapted to carry and to make and break high voltage power currents, as well as to interrupt short circuit currents of large magnitude, with minimum contact deterioration and heating.

A further object of the present invention is to provide a new and improved circuit breaker structure in which the mounting for the movable contact structure serves as a fluid conducting means.

A still further object of the present invention is to provide a new and improved circuit breaker structure in which a pneumatic arc extinguishing device and its actuating means are both isolated at substantially ground potential from the high voltage circuit of the breaker.

A still further object of the present invention is to provide a new and improved circuit breaker structure in which a blast of fluid under pressure from a pneumatic arc extinguishing device, isolated at substantially ground potential from the high voltage circuit of the breaker, is conducted to the zone of arc initiation in the breaker by means which include a fixed conducting member of high dielectric and flashover strength.

Objects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 is a view in vertical cross section of a magnetic blowout type circuit breaker employing the present invention;

Fig. 2 is a partial side view of the pneumatic means and contact structure shown in Fig. 1;

Fig. 3 is an enlarged partial view of the contact structure of Fig. 1 shown in closed position;

Fig. 4 is a cross sectional view through the contact structure of Fig. 3 taken along the line IVIV;

Fig. 5 is a cross sectional view through the bearing of Fig. 4 taken along the line V--V;

Fig. 6 is a cross sectional view through the bearing of Fig. 3 taken along the line VIVI;

Fig. 7 is a cross sectional view through the contact structure of Fig. 3 taken along the line VII-VII;

Fig. 8 is a partial view in vertical cross section of a modification of the contact and are chute structure of the magnetic blowout type of circuit breaker illustrated in Fig. 1;

Fig. 9 is a view of a modification of the bearing structure shown in Fig. 5; and

Fig. 10 is a view of a modification of the fluid conducting tubular members shown in Figs. 1 to 9 embodying this invention.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a magnetic blowout type of circuit breaker employing an arc chute of any suitable form into which the arc is forced by the magetic blowout field and extinguished. The power circuit to be interrupted includes relatively movable contacts between which the arc is formed when the contacts separate at the entrance to the arc chute. Specifically, the contacts comprise a fixed contact structure 11 and coacting movable contact structure 12. The fixed contact structure is electrically connected to a lead-in conductor stud 13 defining one terminal of the breaker, and the movable contact structure 12 comprises a pivoted switch arm having an arcing contact mounted at one end thereof and electrically connected to a conductor stud 15 defining the other breaker terminal. The pivoted contact structure 12 is suitably operated between open and closed circuit position by an operating rod 16 that is connected through a crank 17 to a solenoid or other operating means 18.

Fig. 1 illustrates the movable contact structure 12 in contact open position, the coacting main and arcing contacts 20 and 22, respectively, of the movable contact structure 12 being spaced apart from corresponding main and arcing contacts 23 and 25, respectively, of the fixed contact structure 11. A pair of lugs 21 (one of which is shown in Fig. 1) are integrated with arcing contact 22 and extend from opposite sides of a web portion of arcing contact 22. Lugs 21 together with the web portion of the arcing contact 22 form an engaging surface Q Q; which coacts with that of a loose-fitting, self-aligning block of insulating material 24 on the stationary contact structure ill. to limit overtravel of the movable contact structure 12 in the closing direction. In breaker closed position the stationary arcing contact 25 is shunt-ed by stationary main contact Opening ofthe breaker by the clockwise rotation of the breaker movable contact structure 12 causes in the sequence named separation of the main current carrying contacts 20, 23 and the arcing contacts 22, 25. The power are isformed at the entrance of an arc chute 26 of any suitable known type.

Arc chute 26 is illustrated as being provided with magnetic blowout means comprising blowout coils 28 and 29" arranged so as to cause the are formed between the con tacts 22 and 25 to be blown by the magnetic field into arc chute 26. Blowout coil 28 is connected at one end thereof to an arc runner 3d and at the other end thereof immediately adjacent main contact 23. Blowout coil 29 is connected at one end thereof to an arc runner 31 and at the other end thereofto a lower terminal extension 32 through a conductive bar 66.

Upon separation of the arcing contacts 22' and 25 in a circuit interrupting action the arc terminal is transferred from stationary arcing contact 25 to arc runner 30, thereby inserting blowout coil 28 in the arcing circuit traced from the point of connection of blowout coil 30 on the upper terminal block immediately adjacent main contact 23 through blowout coil 28 to are runner 30, through the arc to movable arcing contact 22. As the arc, now established between arc runner 30 and the movable arcing contact 22, is attenuated by the clockwise rotation of contact structure 12, the arc envelops the lowermost portion of arc runner 31 thereby transferring the arc terminal from arcing contact 22 to are runner 31 and inserting blowout coil 29 in the arcing circuit. The arcing circuit is now completed through the bar 66 which connects the blowout coil 29 with the lower terminal extension 32.

Referring more particularly to the movable contact structure 12 of one phase of a three phase circuit, the switch arm comprises a pair of spaced plates mounted on a pivot bolt 36. The spaced plates 35 are also interconnected by a pin 37 which serves to connect the switch arm to the operating rod 16. Secured to the plates 35 and mounted on bolt 36 with the spaced plates 35 are a pair of spaced plates 38. Plates 38 extend generally parallel along the inside surfaces of plates 35 and are joinedtoplates 35 by any suitable means such as rivets 40. Plates 38 are joined together at their outer extremity by' the contact body or head forming the current carrying contact 20 and the arcing contact 22.

Arranged between the spaced plates 35 and 38 is a hollow fluid conducting stationary bearing 39 for the reciprocating switch' arm or movable contact structure 12. This bearing-may be made of any suitable material sufilciently strong to stand the shock of circuit breaker operations such' as cast bronze.

Bearing 39, more particularly, is arranged between conducting extensions 32 on bolt 36. Spaced plate combinations 35, 38 are yieldingly biased toward each other andagainst the opposite sides of bearing 39 by any suitable means which, for example, may be spring washers 33 secured to bolt 36 by a nut 34. Washers 33 are held in'st'ressed condition against the sides of spaced members 35 by bolt 36 and nut 34, thus providing high contact pressure. Conducting ring inserts 41 are provided betweenplates 38 and conducting extensions 32 to provide a line contact between the stationary and movable parts ofthis' hinge connection. Bolt 36 which passes through suitable openings provided in spaced members 35, 38, extensions 32 andbearing 39', is provided with a closely fitting collar or shield 42 which serves to form a substantially fluid tight connection between the hollow openingin b'earing'39"- and'the bolt 36.

The arcingcontact structure and the arc chute of the circuit breaker structure are mounted on a supporting.

structure comprising a fabricated vehicular base structure 45. Mounted on base structure 45 is the circuit breaker operator 18 which may be a solenoid, pneumatic, or a pneumo-oscillated hydraulic type of circuit breaker movable contact actuating means. A pair of dual purpose substantial vertical or diagonal tubular members 46 are provided on base structure 45. Members 46 are connected to a horizontally arranged manifold 49 which supports a pair of horizontal cross bracing means 47. The circuit breaker elements comprising the movable contact mechanism of the circuit breaker and the arc chute are mounted on the horizontal cross bracing means 47 and the manifold 49. Members 46 in addition to supporting the circuit breaker, further collect and distribute to a zone of arc initiation fluid under pressure from a source of fluid under pressure such as a suitable pneumatic means 48 used for aiding in cooling and extinguishing an arc drawn by the circuit breaker elements between the arcing contacts.

This pneumatic means as illustrated in Figs. 1 and 2 comprises a pair of air pumps comprising cylinders 50 mounted on base structure 45 and pistons 51 movable in cylinders 50. The pistons 51 are biased in contact opening direction by operating springs 59 which are the means for opening the circuit breaker. The pneumatic means 48 serves a plurality of functions, namely, it is the motor actuating means for opening the contacts of the circuit breaker, it acts as an. air pump to force air through the bearing 39 and nozzle 58 to aid in cooling and extinguishing the arc, and it acts as a shock absorber to retard the movement of the switch arm near the end of its opening stroke to reduce the impact of the movable contact structure 12 on the fixed structure of the circuit breaker. The solenoid operating means 18 through crank 17 returns piston 51 to its contact closed position after a circuit breaker opening operation and compresses spring 59 so it is capable of again opening the circuit breaker contacts. Any suitable means such as pipe connections 52 may be used for connecting the substantially vertically arranged tubular members 46 to the source of fluid under pressure, namely cylinders 50. v

Manifold 49 is connected to the bearing 39 of each switch arm of each phase of the three phase circuit breaker through insulating tubular members 54. Bearing 39 comprising a hollow cylindrical member is provided with an outlet 55 (more clearly shown in Figs. 4 and 6). A slip ring 56 having attached thereto a tubular member 57 of high dielectric and flashover strength which terminates at its outer end in a nozzle 58 arranged adjacent the breaker elements in the zone of arc initiation is mounted around trunnion 39. Tubular member 57 is attached to the switch arm for movement therewith. As shown in Fig. 1, tubular member 57 is generally arranged parallel with the switch arm in a predetermined relationship with the contacts 20 and 22. Slip ring 56 is arranged to provide a passageway for air under pressure from cylinder 50 through tubular member 46, manifold 49, tubular member 54, bearing 39, tubular member 57, and nozzle 58 to the zone of arc initiation. Tubular member 57 and nozzle 58 are secured to spaced plates 38 so that slip ring 56 and nozzle 58 move concurrently with plates 38 upon actuation of the arcing contacts to circuit open or circuit closed position.

For the purpose of interrupting either low or high current arcs the switch arm or movable contact structure 12 is connected to piston 51 through operating rod 16, crank 17 and a piston rod 60. Upon the movement of contact structure 12 from closed to open circuit position under the action of springs 59, piston 51 is actuated and moved from the top of cylinder 50 to the bottom of cylinder 50. This movement of piston 51 causes air in cylinder 50 under piston 51 to flow through pipe connections 52, tubular member 46, manifold 49, tubular member 54, bearing 39, tubular member 57 and nozzle 58 to the zone of arc initiation. This blast of air under pressure cools the arc and drives it into the arc chute 26 for rapid arc extinguishing action.

This compact circuit breaker structure has the pneumatic means 48 comprising one or more air pumps and the operating means 18 fixed to the frame structure 45 and both at substantially ground potential. The cylinder 50 of the pumps is metallic and arranged to stand the shock of rapid circuit breaker action and the inherent shock absorbing function performed by the pumps on the movable contact structure 12 as they impel the flow of fluid from cylinders 50 through pipe connections 52 during a circuit breaker opening operation.

The dual purpose tubular members 46 may be fabricated of any metallic material which will support the weight of the arcing contacts and the arc chute structure.

The connection between bearing 39 and manifold 49 is the insulating tubular member 54. Member 54 provides the desired insulation between the operating means at ground potential mounted on the frame structure and the operated means, namely, the arcing contacts at line or system potential. Although this tubular member 54 is made of a hard, strong fabricated insulating material and not apt to rupture or deteriorate, nevertheless, member 54 is so arranged that if it should break so as to cause the pneumatic means to fail to perform its designed function, the circuit breaker structure would not be damaged or destroyed by flashover to ground through the solenoid operator 18 or the pneumatic means 48. This is an important feature when it is necessary to repair and place back in service this particular breaker in a minimum of time after a ruptured fluid conducting member has failed.

Further, a ruptured member 54 would not fully incapacitate the breaker. The breaker could still perform and would be able to complete a circuit interrupting action although this interrupting action might take longer than a circuit interrupting action in which the pneumatic means 48 was functioning properly to aid in extinguishing an arc.

The particular compact arrangement of the circuit breaker components as arranged on the frame structure 45 provides a rugged circuit breaker structure which is easily assembled and repaired. This structure utilized operating means for the purpose of supporting the contact and are chute structure. In this manner, the structure may be assembled with a minimum of parts at a cost below that of a comparable prior art structure of a lower current interrupting capacity.

Figs. 8 and 9 illustrate a modification of the contact structure shown in Figs. 1 to 7, wherein a tubular member 64 and nozzle 65 are fixed and retain a given position during a circuit breaker operation. Slip ring 56 is secured to bearing 39 in this modification by a set screw 63 so that member 64 directs a fluid blast from hearing 39 to a predetermined position in the zone of arc initiation during the complete circuit breaker operation to drive the are into the proper region of the arc chute.

Fig. illustrates a modification of the fluid conducting bearing and tubular means shown in Figs. 1 to 9 wherein member 54 of Figs. 1 to 9 is replaced by a composite tubular fluid conducting member 67. Member 67 bent in a tortuous manner is connected at one end to the cylinder 50 of the pneumatic means 48 through manifold 49 and extends to and around a bearing 68 of the movable contact structure and terminates at the other end in a nozzle directed toward the zone of arc initiation. Tubular member 67 comprises insulating portions 69 and 70 of high dielectric and flashover strength interconnected by a metallic portion 71. Suitable means for securing tubular means 67 to bearing 68 to fix the nozzle in a predetermined relationship to the arcing contacts is provided.

Although but a few embodiments of the present invention have been illustrated and described, it will be ap 6 parent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. An electric circuit interrupting device comprising a pivoted switch arm having an arcing contact mounted at one end thereof, a coacting fixed arcing contact, a hollow fluid conducting stationary bearing for said switch arm, means for operating said switch arm between open and closed circuit positions, pneumatic means for extinguishing an are drawn between said arcing contacts comprising a cylinder and a piston movable in said cylinder, said piston being actuated upon movement of said switch arm, a tubular member of insulating material connected at one end to said cylinder and at the other end to said bearing, and a second tubular member connected at one end to said bearing and terminating at its other end in a nozzle in the zone of arc initiation, said tubular members conducting fluid from said cylinder to said arcing zone upon movement of said piston in contact opening direction.

2. An electric circuit interrupting device comprising a pivoted switch arm having an arcing contact mounted at one end thereof, a coacting fixed arcing contact, a hollow fluid conducting stationary bearing for said switch arm, means for operating said switch arm between open and closed circuit positions, pneumatic means for extinguishing an are drawn between said arcing contacts comprising a cylinder and a piston movable in said cylinder, said piston being actuated upon movement of said switch arm, a tubular member of insulating material connected at one end to said cylinder and at the other end to said bearing, and a second tubular member arranged in fixed relationship to said switch arm and connected at one end to said bearing and terminating at its other end in a nozzle in the zone of arc initiation, said tubular members conducting fluid from said cylinder upon movement of said piston in contact opening direction.

3. An electric circuit interrupting device comprising a pivoted switch arm having an arcing contact mounted at one end thereof, a coacting fixed arcing contact, a hollow fluid conducting stationary bearing for said switch arm, means for operating said switch arm between open and closed circuit positions, pneumatic means for extinguishing an are drawn between said arcing contacts comprising a relatively fixed cylinder and a piston movable in said cylinder, said piston being actuated upon movement of said switch arm, a tubular member of insulating material connected at one end to said cylinder and at the other end to said bearing, and a second tubular member pivotally connected at one end to said bearing and disposed generally parallel to said switch arm and terminating at its other end in a nozzle in the zone of arc initiation, said tubular members conducting fluid from said cylinder upon movement of said piston in contact opening direction.

4. An electric circuit interrupting device comprising a pivoted switch arm having an arcing contact mounted at one end thereof, a coacting fixed arcing contact, a hollow fluid conducting stationary bearing for said switch arm, means for operating said switch arm between open and closed circuit positions, pneumatic means for extinguishing an are drawn between said arcing contacts comprising an insulating cylinder and a piston movable in said cylinder, said piston being actuated upon movement of said switch arm, a tubular member of insulating material connected at one end to said cylinder and at the other end to said bearing, and a second insulating tubular member pivotally connected at one end to said bearing and attached to said switch arm for movement therewith and terminating at its other end in a nozzle in the zone of arc initiation, said tubular members conducting fluid from said cylinder upon movement of said piston in contact opening direction to extinguish the arc.

5. An electric circuit interrupting device comprising a vehicular fabricated base structure, a circuit breaker operator mounted on said base structure, a dual purpose substantially vertically arranged tubular member for supporting a circuit breaker and for distributing fluid under pressure, horizontal cross bracing means supported by said operator and said substantially vertically arranged tubular member, circuit breaker elements mountedon said cross bracing means comprising. a pivoted switch arm having an arcing contact mounted atone end thereof, a coacting relatively fixed arcing contact, and a hollow fluid conducting stationary bearingfor said switch arm, said operator arranged for actuating said switch arm between open and closed circuit positions, pneumatic means for extinguishing an are drawn between said arcing contacts comprising a, cylinder mounted on said base structure and a piston movable in said cylinder, means for connect.- ing said substantially vertically arranged tubular support member to said cylinder and said bearing and a second tubular member connected at one end to said bearing and terminating at its other end in the zone of arc initiation, said pneumatic means supplying, fluid under. pressure through said tubular members to said arcing zone upon movement of said switch arm to circuit open position.

6. An electric circuit interrupting device comprising. a vehicular fabricated base structure, a solenoid operator mounted on said base structure, a dual purpose substantially vertically arranged tubular. member for supporting a circuit breaker and for distributing fluid under pressure, horizontal cross bracing meanssupported by saidsolenoid operator and said substantially vertically, arranged tubular member, circuit breaker. elements mounted on said cross bracing meansv comprising; a pivoted switch, arm having an arcing contact mounted at one end thereof, a coacting relatively fixed arcing contact, a hollow fluid conducting stationary bearing for said switch arm, spring biasing means for actuating said arcing contacts to open circut position, said solenoid operator arranged for actuating said switch armfrom open to closed circuit position, pneumatic means for extinguishing an are; drawn between said arcing contacts comprising a. relatively fixed cylinder mounted on, said base, structureanda piston movable in said cylinder, means for connecting said. substantially vertically arranged tubular supportmember to, said cylinder to said bearing and, a, second, tubular member connected at one end to said bearing and, terminating at its other end in a nozzle in the zone of arc initiation, said pneumatic means supplying fluid under pressure through said tubular member to said arcing zone upon movement of said switch arm to circuit open position.

7. An electric circuit interrupting device comprising a vehicular fabricated base structure, a solenoid operator mounted on said base structure, a dual purpose substantially vertically arranged tubular member for supporting a circuit breaker and for distributing fluid under pressure, horizontalcross bracing means supported by said solenoid operator and said substantially vertically arranged tubular member, circuit breaker elements mounted on said cross bracing means comprising a pivoted switch arm having an arcing contact mounted at one end thereof, a coacting relatively fixed arcing contact, a hollow fluid conducting stationary bearing for said switch arm, spring biasing means for actuating said arcing contact to open circuit position, said solenoid operator arranged for actuating said switch arm from open to closed circuit position, pneumatic means for extinguishing an are drawn between said arcing contacts comprising a relatively fixed cylinder mounted on said base structure and a piston movable in said cylinder, means for. connecting one end of said substantially. vertically arranged tubular support member to said cylinder, a second insulating tubular member interconnecting said support member and said bearing, and a third tubular member connected at one end to said bearing and terminating at its other end in a nozzle in the zone of arc initiation, said pneumatic means supplying fluid under pressure through said tubular members to said, arcingzone uponmovement of said switch arm to circuit open position.

8. An electric circuit interrupting device comprising a pivoted switch arm having an arcing contact mounted at one end thereof, a coacting fixed arcing contact, a hollow fluid conducting stationary bearing for said switch arm, pneumatic means for said circuit breaker comprising a cylinder, apistonmovable in said cylinder, a piston rod connected, to said switch arm, and spring means for actuating said piston in contact opening direction, a tubular member of insulating material. connected at one end to said cylinder; and. the other end to said bearing, and a second tubular member connectedat one end to said bearing and terminating at its other end in a nozzle in the zone of arc initiation, said tubular member conducting fluid from said cylinder upon movement of said piston in contact opening direction, said pneumatic means retardingthe movement of, said switch arm asit nearscircuit open position.

References Cited in the file of this patent UNITED STATES PATENTS 1,887,545 Cohn et al. Nov. 15, 1932 2,330,820 Fernier Oct. 5, 1943 2,347,984 Baskerville May 2, 1944 2,399,485 Harlow et al. Apr. 30, 1946 2,491,964 Frink Dec. 20, 1949 2,734,971 Lingal et al. Feb. 14, 1956 FOREIGN PATENTS 200,158 Switzerland Dec. 16, 1938 457,442 Great Britain Nov. 27, 1936 487,391 Great Britain Sept. 11, 1936 Germany Apr. 16, 1937 

